/diy/ - Do It Yourself

Do you even know what those words mean?

>>1398292
Omfg so good.

Physics student with no practical knowledge posting on diy. Priceless.

>>1398292
>retarded idea
yes

>>1398294
i know its stupid but if volts equal speed of the engine and amps the possible torque then if i convert the speed to torque it should be possible to do so making a mechanical transformer

>>1398299
i know im making a mechanical transformer

>>1398302
You mean a gearbox?

"mechanical transformer"

>>1398308
yes

>>1398310
Just no.

>>1398302
youre going to rewind the motors every time you want to change the output?

>>1398292
i wish every damn electrcian/self taught electronics hobbyist would read this thread.

this is why those who know, actually use E=IR instead of the pleb V=IR. Electromotive Force is measured in voltage. it's like calling gasoline/petrol liters/gallons

OP isn't even smart enough to convert horse power to joules and torque to newton meters and then to watts/time (volt-amps if you use a RMS meter).


>>1398308
Shhh. OP hasn't smoked enough yet to come up with digital and anolog mechanics on his own.

Okay maybe I'm just dumb but what is so retarded about this other than that he's calling a gearbox a "mechanical transformer"

I was under the impression gear boxes were used in turbines for this purpose

>>1398407
A transformer does exactly what he wants to do with vastly fewer points of potential failure and will do so much more efficiently since it isn’t affected by friction... which is why everyone uses transformers already instead of coupling generators and motors together just to change the voltage...

>>1398407
Also in a turbine your converting steam pressure into electricity via a generator... op wants to use an electric motor to take electricity of one voltage and then use it to turn another generator to produce electricity at a different voltage

>>1398412
I knew it was retarded to do instead of a transformer for the purpose he was trying to achieve, I just wasn't sure if there was something else retarded I was missing.

Tbh if he's doing it just for the novelty of it I don't see the problem unless he genuinely thinks he's coming up with a solution to a problem

>>1398416
Generally judging by the phrasing of his post (and being an expert for having seen many of these posts in my time) I would suspect op is under the impression he has a good idea that might even catch on.. usually If it’s a novelty or school project that gets mentioned.

>>1398300
I think for you, hydraulic analogies would work better.
Think of the water from a water tower coming down a pipe and then back up to a faucet.
The voltage (potential voltage like gravitational potential energy) would be the height of the water tower. The water in the piping can only go back up to the same level as the water in the tower, a 10 foot tower can't feed a faucet on top of a 20 foot building, it doesn't have the pressure or potential energy available to push it.
The current measured in amps would be the size of the pipe (consider why wires are rated to carry X amps at some size), no matter how high the water tower, you can't get 100 gallons per minute flow out of a pipe the size of a drinking straw.
This analogy works with batteries too. Series wired (connected 1 to another in a long row) batteries raise voltage like a higher tower.
Parallel wired batteries (connected wide, all the +connected together on one end and all the - connected at the other end) raise the current capacity, just like a wider pipe.

AC and transformers are just magic. You run electricity through a coil to create a magnetic field like in an electromagnet, store energy in the magnetic field floating in the air, then when the electricity stops, the field collapses and dumps energy into the coil(s) to go back to electricity. The winding of the coils determines ratios etc

>>1398412
>>1398416
If he is trying to make a DC equivalent to a transformer, go analog or go buck/boost or sink, or generic voltage regulator, etc
Don't try and tell him to run a transformer with for DC conversion.

>>1398433
The dc equivalent of a transformer is a fucking transformer with an inverter and rectifier you knob. And while more complex than an ac transformer it is still less complex than the rube Goldberg contraption op is suggesting.

>>1398433
Also not to be pendatic but you could feed water to the top of a taller tower provided you had enough supply on the shorter one and you used a ram pump at the bottom

>>1398292
I'm assuming you mean to convert the output of a CV high-voltage, low-current power supply into a CV high-current, low-voltage power supply. A buck-boost converter will do that far more efficiently than any mechanical device, or even a transformer if you're going AC (which you probably aren't).

Though similar devices to what you're suggesting are used to provide very short bursts of high current, basically electric flywheels with an input winding and an output winding. The Gerald R. Ford-class aircraft carrier plans to use such a system instead of a capacitor bank to release the energy to its electromagnetic aircraft catapult. Note that this requires taking a long time to spin up the flywheel with a presumably finely-wound stator windings, and discharge through seperate coarsely wound stator windings. The advantage of this is you get a lower voltage and higher current, which for a big coilgun/railgun is preferable.

But if you planned to convert the output of a CV high-voltage, low-current power supply into a CC high-current, low-voltage power supply, it wouldn't be very possible at all without some nutty CVT feedback. CC and CV stand for constant-current and constant-voltage, btw.

>>1398377
But electromotive force is a more general term that refers to any force that moves charges, including gravity in the right circumstances. And that's even forgiving the "potential != force" problem. I agree that "voltage" is a bit silly, but surely terms like "electric tension" or just plain "potential" make more sense. I know they do in other languages. Also "Vcc" and such is already far too embedded into our nomenclature.

>>1398451
It's called a hydraulic boost converter.

>>1398377
I see why using "V" in Ohm's law is problematic as it stands for a unit of measurement, which is why I know it as U = RI, but calling an electrical potential difference a "Force" sounds very wrong and the use of this term is rather archaic and deprecated according to IEC.
Also using E in Ohm's law is still confusing as it could also denote the electrical field and then it looks like you are intermingling the microscopic (E = jp) and macroscopic version of it.

>>1398587

At the end of the day, current is determined by voltage, whether the voltage is applied by an external source or is generated by magnetic fields. Arguing about force and potential and crap like that is just semantics.

On the other hand, a rigorous analysis of what goes on inside an electromagnetic device is not trivial, mainly because magnetic fields are nearly impossible to model precisely.

t.former motor designer

>>1398587

Well there isn't any issue with the "V" referring to both the unit and the measurement. Unit's aren't typically put into an equation anyways. In some uses a lowercase "v" is used for voltage/pontential.

>>1398595
As a physics student, I've learnt that magnetic and electric fields are fairly straightforward to calculate via Maxwell's equations. Solving numerically, if you have enough computation time it should be possible to obtain a dynamic model of an electromagnetic device that's more than accurate for any practical use. Though that's not to say that quantifying what design change would result in what performance change would be easy.

>>1398298

>Student

Says it all.

>>1398596
>Solving numerically, if you have enough computation time

I agree, student. Go for it.

>>1398596
As a fellow physics student who had to model the magnetic field of a real coil in an internship for a company, let me tell you i was happy they had a rather powerful cluster and one of them expensive ANSYS licenses.

>>1398598

Hiring a new designer out of college was always hilarious. The rate at which he or she learned that the precise equations they were used to had little or no relation to real world design was a good indicator of how well they would fit in.

I can remember when I first actually realized what "significant digits" really meant, and why I had been so retarded to have ever written down an answer like 7.14842 on an exam. In the real world, you are usually happy to know if it's 7.1 plus or minus 10 percent.

>>1398292
i just skimmed the thread, but you can't really "convert" volts to amps and vice versa using a gearbox analogy.

now, there are equivalent transforms between mechanical and electrical systems. for example, the transmission in a car (or any gear reduction) is equivalent to an electrical transformer. Electrical transformers do not convert amps to volts, they only keep the product of V*A equal. Likewise, transmissions keep the product of angular speed and torque the same.

And if you want to boil things down to simple machines, transmissions and transformers are the linear mechanical equivalent of a lever and fulcrum. With a lever, you can lift a very heavy item yourself with little force, but to keep the work input the same as the output, you input large displacement. so large displacement with low force is "transformed" into small displacement with large force. So the product of force*distance remains the same.

So just remember that with linear, angular, or electrical lever systems, the amount of work or power you put in is the same as you get out on the other end.

>>1398609
>the amount of work or power you put in is the same as you get out on the other end.

in the real world, devices usually have losses that have to be considered, whether electrical or mechanical or whatever, and sometimes the losses are significant.

>>1398603
I tell /sci/ this all the time, they never listen.

>>1398292
>voltage to amperage converter and vice versa using a 1:10 gearbox or 3d printed cvt and dc motors

>>1398598
Are you mocking me? I can't tell.

>>1398600
Yeah, while I trivialised it I imagine the differential equations involving not only time-dependancies but also all the different permeabilities must be a right pain. To say nothing of the skin-effect messing with your current densities, but for the most part I think you should be able to ignore those for ±1%.

>>1398708
>ignore those for ±1%.

Are you talking about an air coil with no ferromagnetic material? When you say that the equations are so exact and all you need is a big computer you have to be either unfamiliar with actual ferromagnetic material or you are not going to be using it.

Try to find laminations where you can compute the flux density at 1 percent, whether you are using just coils or heaven forbid some rare earth magnets which themselves cannot be characterized that precisely.

I'm done arguing in this thread because it's just internet bullshit, but you are so academic it's hilarious.

>>1398713
Well it's just that the skin-effect could just be treated as an increased resistivity in the wire with the current still with a uniform density, as the resultant field wouldn't change too much. Particularly when any magnetic cores aren't right up against the wires, and when there's a lot of densely-packed windings. But I'm surprised that such a thing as silicon steel laminations or a rare-earth magnet cannot be characterised well. Is it just imperfections in the material? Otherwise there simply aren't any unknowns that would lead to such a large uncertainty.

>>1398713
How useful is modeling a coil in reality? When designing a flyback transformer, nothing fancy for a company mind you, just diy stuff, the design equations are fairly simple.

Mine design used a molypermalloy core with distributed air gap operating at like 100kHz I think? No Maxwell equations or any fancy theory required. I don't even get why that's important? Why would I need to know the number of magnetic field lines or whatever going through the core? How do I apply that?

>>1398723
It would be useful for MHz/GHz RF applications where stray capacitance and skin-effect and such really matter, not that you'd be using any kind of big coil at GHz frequencies.

>>1398728
I don't think I'll ever fully understand all the weird shit with RF

>>1398734
the fuck

>>1398613
no shit, sherlock.

>>1398743
the capacitances are kind of easy to imagine wrt a ground plane on the other side of the board. what i have a harder time with is inductance of a straight run of wire.

>>1398723
modeling transformers is not a exact science theres a lot of methods for calculating.

building the tranny is the real tricky part, for high frecuencies and max efficiency you need to do "interleaving" (like making a sandwich with many layers using the primary and secundary windings) this is very time consuming so many times the trannys are made with regular windings just two layers primary and secundary this is very inefficient at high frequencies but cheap to produce.

>>1398720
>I'm surprised that such a thing as silicon steel laminations or a rare-earth magnet cannot be characterised well

Some materials simply cannot be characterized precisely. I'm not sure why, but it's a fact. Look at any neodymium iron boron spec, and it's always specified as a minimum or a typical value. Unless you pay a lot for someone to screen your magnets, you simply cannot specify that a magnet have a specific strength.

Same goes for laminations. Steel alloys are not a precise material in almost any respect, from the alloy percentages to the effects of heat treating.

You can calibrate a device to a degree by machining it, such as grinding the rotor of a motor that has permanent magnets in the rotor, but as for computer calculations it is not a matter of having a powerful enough computer or sophisticated software, because the physical materials simply cannot be specified to a great deal of precision.

>>1398836

note to self: find some other way to say "simply". Or even better, just leave it out.

>op comes up with retarded idea
>everyone simultaneously agrees that it's a stupid idea
>thread still manages to turn into an in depth argument

what the fuck

>>1398889
It's just a "look how smart i am" shitfest now.

>>1398889
>what the fuck

marry me. or her.

>>1398891
>It's just a "look how smart i am" shitfest now.

I didn't post any credentials

>>1398892
>>1398893
I've seen you before and you always post irrelevant schizo shit and these images

what's goin on big guy?

>>1398898
>I've seen you before and you always post irrelevant schizo shit and these images

schizo

my main troll image folder is "australia"

>>1398900
>schizo
>lolis

we all know lolis don't into maffs. moar liek pic related, amirite?

>>1398292
It’s like Tesla reincarnated.

>>1398898
Choose your next words carefully, big guy. That's my wife you're talking about.

>>1398603
The amount of significant digits is entirely dependent on the application, didn't you get taught that?

>>1398292
Sage

>>1399881
Good post, read the fucking rules.